JPH02230571A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To set a data head in a prescribed position on a data track even when a servo track has a defect by performing a magnetic head positioning control using a signal at a reset level when a position error signal level falls within a prescribed level range. CONSTITUTION:When a position error signal 101 of an output of a demodulating means 4 falls within a prescribed level range, this position error signal is inputted to an amplifying means (addition amplifier) 5 to carry out the magnetic head positioning control, and when a position error signal falls into the prescribed level range, a preset prescribed level signal is inputted from a selection control signal generator 12 to the amplifying means 5 to carry out the magnetic head positioning control. By this method, even when a servo track has a defect and hence the position error signal is distorted, the magnetic head positioning control can be carried out without responding to this distortion, and then the data head is controlled to be set in a prescribed position on a data track, thus reading out a data normally.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic disk device, and more particularly to a servo track type magnetic disk device with improved magnetic head positioning control means.

(Prior art) Conventionally, a magnetic disk device that uses the servo track method reads servo information written on a servo disk using a servo head, and performs magnetic recording based on the position error signal of the servo head obtained by demodulating the servo information. Positioning control is performed to set the head at a predetermined position. A conventional example will be described below with reference to the drawings.

FIG. 3 is a block diagram of the magnetic head control part of a conventional magnetic disk device, where ] is a servo disk recording servo information, 2 is a servo head that reads servo information from servo disk 1, and 3 is an output signal of servo head 2. 4 is a demodulator that demodulates the output signal of amplifier 3 and outputs the position error signal 101; 5 is the position error signal 1
6 is a current amplifier that amplifies the output signal of the summing amplifier 5, 7 is a voice coil motor driven by the current amplifier 6, and 8 is a magnetic head positioner connected to the voice coil motor 7. Opportunity, 9-
1 to 9-N (N is a natural number) are data disks for writing/reading data, and 10-1 to 10-N are data heads corresponding to data disks 9-1 to 9-H.

Next, the operation of the magnetic head control portion shown in FIG. 3 will be described. The servo information written on the servo disk 1 is read out by the servo head 2, and the output signal of the servo head 2 is input to the amplifier 3. The amplifier 3 amplifies the output signal of the servo head 2 to a predetermined level, and inputs the amplified output signal to the demodulator 4. The demodulator 4 demodulates the input signal and outputs a position error signal 101 of the servo head 2.

The position error signal 101 is a signal that changes as the servo head 2 deviates from a predetermined set position.

For example, as shown in the waveform diagram of the position error signal in Figure 4,
The servo head 2 transfers the servo head 2 to the servo disk 1 from the rack 21-1 to the rack 21-2 (the 1 rack in which the servo information is written) written on the servo disk 1.
2 (in the direction of the arrow), the position error signal 101 is generated at the border of the adjacent Zapo 1 rack (for example,
When servo F2 is positioned at the boundary between servo 1 and racks 21-1 and 21-2, or between servo 1 and rack 21-2 and rack 21-3, etc.), the potential level becomes zero, and servo head 1 -2 changes to a level (greater or smaller than the zero potential level) as it moves away from the boundary. Normally, the predetermined set position of →no-bo head 2 is the position at the boundary between the adjacent servo 1 and the rack where the position error signal 101 is zero potential level, and by controlling and setting the servo head 2 at this position, the magnetic head is Positioned. In FIG. 3, the position error signal 101 output from the demodulator 4 is input to the summing amplifier 5.

The summing amplifier 5 controls the voice coil motor 7 via the current amplifier 6 so that the level of the input position error signal 101 becomes zero potential l/bel. Voice coil motor 7
A magnetic head positioning device 4M8 connected to the servo head 2 and a plurality of data heads (data heads 10-1 to 10-N) are attached to the magnetic head positioning machine 4M8, which controls the operation of the voice coil motor 7. The magnetic head moves accordingly. By controlling the voice coil motor 7 so that the level of the position error signal 101 at the input of the summing amplifier 5 becomes zero potential level, the ZARPOHEET 2
The position of the data heads IO-1 to IO-N is controlled to always be at a predetermined set position (the boundary position of adjacent servo tracks), and thereby the data heads IO-1 to IO-N are also positioned on the data disks 9-1 to 9-N. Positioning can be controlled at a predetermined position.

(Problem to be Solved by the Invention) However, in the conventional magnetic disk drive described above, positioning control is performed on the magnetic head 1 based only on the position error signal of the servo head. , zero potential level), the magnetic head positioning control corresponding to this position error signal is performed, and the data head is set at a position deviated from the predetermined position on the data track, so that data can be correctly transmitted. The disadvantage is that it cannot be read.

For example, as shown in the relationship between the position error signal and the data head position in FIG.
If a defect 22 exists at the -2 boundary, distortion 23 will occur in the position error signal 101 when the servo head 2 comes to this position, and the level of the position error signal 101 will be at a level that deviates from the zero potential level. Therefore, this position error signal 101
The magnetic head positioning control is performed based on the servo tracks 21-1 and 21-2.
2, that is, the distortion 2 of the position error signal 101
At point 3, the data head (for example, data head 10-) is set at a position that is far away from the predetermined position corresponding to the data track (track where data is written) 24, and data cannot be read. The drawback is that it does not work properly.

An object of the present invention is to provide a magnetic head that detects a position error signal level and uses the position error signal when the position error signal level is within a predetermined level range. Magnetic head positioning control that performs positioning control and uses a signal at a preset predetermined level (for example, zero potential level) without using the position error signal when the position error signal level is outside a predetermined level range. It is an object of the present invention to provide a magnetic disk device which can set and control a data head to a predetermined position on a data track even if a defect exists in the servo track.

(Means for Solving the Problems) In order to achieve the above object, the present invention has the following means configuration.

That is, the magnetic disk device of the present invention reads servo information written on a servo disk with a servo head, and performs magnetic head positioning control based on a position error signal obtained by amplifying and demodulating the servo head output signal. A track type magnetic disk device, wherein the demodulating means outputs the position error signal; selection means for selecting and outputting one of the two input signals; an amplification means for receiving the output signal of the selection means and outputting a magnetic head positioning control signal; and receiving the position error signal output from the demodulation means as input; , compares the level of the position error signal with a predetermined level range set in advance, and corresponds to the distortion generated when the level of distortion generated in the position error signal is outside the predetermined level range. control means to selectively output the predetermined level signal to the selection means during the predetermined time width, and to output the predetermined level signal to the selection means outside the predetermined time width. and a selection control signal generation means for generating and outputting the selection control signal that controls the position error signal to be selectively output.

(Function) The function of the magnetic disk device of the present invention having the above-mentioned means will be explained below.

Servo information written on the servo disk is read out by the servo head, and the servo head output signal is amplified and demodulated. The demodulation means outputs a position error signal of the servo head, and the position error signal is input to the selection means. A predetermined level signal preset to a predetermined level is also input to the selection means.

The selection means selects and outputs one of the two input signals (ie, the position error signal or the predetermined level signal) based on the selection control signal.

The output signal of the selection means is input to the amplification means.

The amplifying means outputs a magnetic head positioning control signal for performing magnetic head positioning control so that the signal level of the input signal becomes a predetermined level (eg, zero potential level). The position error signal output from the demodulation means is also input to the selection control signal generation means.

The selection control signal generation means determines whether the signal level of the position error signal is "within" a predetermined level range (for example, a range of zero potential level ±ΔE, where ΔE is a small positive level); Compare the level of "existence".

Based on the comparison results, the following characteristics are determined with a predetermined time width corresponding to the distortion generated when the level of distortion generated in the position error signal is outside the predetermined level range. A selection control signal is generated and outputted to the selection means. That is, in the predetermined time width, the selection means is controlled to selectively output a predetermined level signal,
Outside the predetermined time width, a selection control signal is generated and outputted for controlling the selection means to selectively output the position error signal.

As a result of the above action, when the position error signal output from the demodulation means is within a predetermined level range (for example, zero potential level ±ΔE), the position error signal is input to the amplification means to perform magnetic head positioning control. If the position error signal falls outside the predetermined level range, a predetermined level signal (for example, a zero potential level signal) is input to the amplification means to perform magnetic head positioning control, so that the data head is always kept at a predetermined position. It can be set in the following position.

(Example) Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a partial configuration diagram of a magnetic disk device according to an embodiment of the present invention, in which 4 is a demodulator that outputs a position error signal 101;
11 is a selector that selects and outputs one of the input signals based on the selection control signal 103; 12 is a selection control signal that generates and outputs the selection control signal 103; generator, 12
-1 is a level detection circuit that compares the level of the position error signal with a predetermined level range set in advance and outputs a level detection signal 102 indicating the comparison result, and 12-2 is a monostable multivibrator circuit. .

Further, FIG. 2 is an explanatory diagram of the operation of the embodiment of the present invention.

The operation will be explained below with reference to FIGS. 1 and 2. Note that the demodulator 4 and the summing amplifier 5 are the same as the components with the same numbers shown in the conventional example of FIG. 3, and detailed explanations thereof will be omitted.

In FIG. 1, the position error signal 101 of the output of the demodulator 4
is input to the selector 11 and the selection control signal generator 12.

A predetermined level signal is connected to the other input of the selector 11. In this embodiment, the predetermined level is the zero potential level. The selector 11 selects and outputs either the position error signal 101 or a predetermined level signal (zero potential level signal) based on the selection control signal 103. The output signal of the selector 11 is input to the summing amplifier 5. The summing amplifier 5 performs magnetic head positioning control so that the input signal (that is, the position error signal 101 or the zero potential level signal) becomes a predetermined level (in this embodiment, the zero potential level). A magnetic head positioning control signal 104 is output. This output signal is a signal for controlling the voice coil motor 7 via the current amplifier 6 to control the positioning of the magnetic head, as shown in the conventional example of FIG.

The level detection circuit +2-1 (a part of the selection control signal generator 12) to which the position error signal 101 output from the demodulator 4 is inputted, detects the signal level of the position error signal 101 and a predetermined level range set in advance. A level detection signal 102 indicating the comparison result is output. For example, as shown in FIG. 2, a ten ΔE level 25-1 and a -ΔE level 25-2 are set, and a zero potential level ±ΔE is set as a predetermined level range. However, ΔE is a small positive level. If the signal level of the position error signal 101 is normal and within the zero potential level ±ΔE range, the logic level is "0", and this is caused by the defect 22 formed at the boundary between the servo tracks 21-1 and 21-2. Distortion caused by
If it is outside the range, a level detection signal 102 of logic level "1" is output.

In FIG. 1, the level detection signal 102 is a monostable multivibrator circuit (a part of the selection control signal generator 12).
12-2. The monostable multi-vibrator circuit 12-2 generates a selection control signal +03 having a predetermined time width when the level detection signal +02 indicates a level comparison result of "outside the predetermined level range". That is, the generated selection control signal 103 is as shown in FIG.
When the position error signal level is outside the range of zero potential level ±ΔE and the level detection signal 102 changes from logic level "0" to logic level "1", logic level "o" becomes logic level "1" and the predetermined The logic level "
This is a signal that maintains a logic level of "1" and then becomes a logic level of "0."

This predetermined time width is greater than or equal to the time width corresponding to the distortion 23. In this embodiment, the selection control signal +03 having a predetermined time width is used as a monostable multi-by-break (M
Although an example has been shown in which the selection control signal 103 is generated using an onostable multivibrator circuit, the present invention is not limited to this circuit, and a similar selection control signal 103 can be generated using another circuit.
It is clear that it is possible to generate In FIG. 1, the selection control signal 1 output from the selection control signal generator 13
03 is input to the selector 11. The selector 11 selectively outputs a zero potential level signal during a predetermined time period when the selection control signal 103 is at the logic level "1", and outputs a zero potential level signal during a predetermined time period when the selection control signal 103 is at the logic level "0". The position error signal 101 is selectively output during a time period other than the time width of . In other words, when the position error signal 101 has a normal signal level and is within a predetermined level range, the position error signal 101 is selected, and when the position error signal 101 has an abnormal signal level and is outside the predetermined level range. , the zero potential level signal is selected and the selection output signal A shown in FIG. 2 is output from the selector 11.

In addition, in the above explanation, the selection control signal 103 that controls the selector 11 is the monostable multi-bi break circuit l2.
-2, but it is not limited to this, the monostable multivibrator circuit l2-2 is deleted, and the level detection signal 102 itself is selected as the control signal +
The selector 11 can also be controlled as 03. In this case, the selection output signal B shown in FIG. 2 is output from the selector 11, and it is clear that the object of the present invention can be achieved.

The output signal of this selector 11 is input to the summing amplifier 5,
The summing amplifier 5 controls the positioning of the magnetic head without responding to the distortion 23 of the position error signal 101.

(Effects of the Invention) As explained above, in the magnetic disk device according to the present invention, when the signal level of the position error signal is within a predetermined level range, magnetic head positioning control is performed using the position error signal, If the position error signal level is outside the specified level range, do not use the position error signal,
Magnetic head positioning control can be performed using a predetermined level signal. Therefore, even if there is a defect in the servo track and distortion occurs in the position error signal, the positioning control of the magnetic head can be performed without responding to the distortion, and the data head can be positioned at a predetermined position on the data track. This has the effect that data can be read normally by controlling the settings.

[Brief explanation of the drawing]

FIG. 1 is a partial configuration diagram of a magnetic disk device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of the operation of the embodiment of the present invention, FIG. 3 is a configuration diagram of a magnetic head control portion of a conventional magnetic disk device, and FIG.
The figure is a waveform diagram of the position error signal, and FIG. 5 is a diagram showing the relationship between the position error signal and the data head position. 1... Servo disk, 2... Servo head, 3... Amplifier, 4... Demodulator, 5... Adding amplifier, 6・・・・・・
Current amplifier, 7...Voice coil motor,
8...Magnetic head positioning mechanism, 9-1 to 9-
N...Data disk, 10-1 to 10-N
...Data head, 11...Selector, 12...Selection control signal generator, 12-1
... Level detection circuit, l2-2 ... Monostable multi-vibration circuit, 21-1 to 21-5 ...
... Servo track, 22 ... Defect, 2
3...distortion, 24...data track, 25-1...+ΔE level, 25-2...
...-ΔE level, 101... Position error signal, 102... Level detection signal, 103.
...Selection control signal, head positioning control signal. 104・・・・・・To magnetism

Claims (1)

[Claims] In a servo track type magnetic disk device, the servo head reads out servo information written on a servo disk, and performs magnetic head positioning control based on a position error signal obtained by amplifying and demodulating the servo head output signal. demodulation means for outputting an error signal; a selection for receiving the position error signal and a predetermined level signal preset to a predetermined level as input, and selecting and outputting one of the two input signals based on a selection control signal; means; inputting the output signal of the selecting means, amplifying means for outputting a magnetic head positioning control signal; and inputting the positional error signal output from the demodulating means; Compare the level with the level range,
has a predetermined time width corresponding to the distortion generated when the level of distortion occurring in the position error signal is outside the predetermined level range, and in the predetermined time width, the selection means control to selectively output the predetermined level signal, and generate the selection control signal to control the selection means to selectively output the position error signal outside the predetermined time width. A magnetic disk device comprising: a selection control signal generating means for outputting;